In the larger U.S. cities, physical deterioration, crowding, and complex socioeconomic factors have produced vast slums. Most urban renewal programs of the mid-20th cent. were aimed at clearing these slums through the demolition of decayed buildings and the construction of low-income and middle-income housing projects. It was found, however, that the mere replacement of old buildings with new structures did not eliminate slum conditions.
In contrast to traditional planning, which concentrated on improving the physical aspects of buildings and streets, modern city planning is increasingly concerned with the social and economic aspects of city living. The process of city planning is a highly complex, step-by-step procedure, usually involving a series of surveys and studies, development of a land-use plan and transportation plan, preparation of a budget, and approval of a unified master plan by various agencies or legislative bodies. City planners are usually part of an urban planning board or governmental agency that must take into account the characteristics and long-range welfare of the people of a particular urban community—their employment opportunities, income levels, need for transportation, schools, shopping areas, hospitals, parks and recreational facilities. They must face the problems of traffic, congestion, and pollution; they must also consider the availability of police, fire, and sanitation services, the limitations posed by zoning and other regulations, and the problems of funding. In recent years, residents of many communities have demanded greater participation in the planning of their own neighborhoods, and some planners have worked closely with community groups during various stages of the planning process.
Contemporary examples of planned cities include Brasília, the federal capital of Brazil, Rotterdam, main seaport of the Netherlands, Chandigarh, the joint capital of the Indian states of Haryana and Punjab, Islamabad, the capital of Pakistan, and Abuja, the capital of Nigeria.